• Title/Summary/Keyword: optical pulses

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Optimization of 40 Gb/s WDM Systems Using Super-Gaussian RZ Pulses

  • Lee, Jong-Hyung;Han, Dae-Hyun;Lee, Yong-Jae;Choi, Byeong-Yoon
    • Journal of the Optical Society of Korea
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    • v.12 no.4
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    • pp.226-231
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    • 2008
  • 40 Gbps WDM Systems using super-Gaussian RZ pulses have been studied by numerical simulation to optimize their performance. The assumption of standard single mode fiber is valid when existing WDM systems are required to upgrade their performance to 40Gbps. It is shown that the standard single mode fiber can transmit optical signals over 720 km (Q > 10) by optimizing optical and electrical filter characteristics at the receiver and by compensation of dispersion. However, it is also shown that ${\pm}0.3%$ dispersion compensation tolerance per span (80 km) could prohibit transmitting over 320km (Q > 10). In addition, a duty cycle of less than 0.4 degrades system performance significantly.

Properties of Distribution of PD Pulses accompanying with Propagation of bush-type Tree (부시형 전기트리의 성장에 따른 부분방전 펄스의 분포 특성)

  • Kang, S.H.;Jung, S.H.;Lee, K.W.;Jang, D.U.;Ryu, B.H.;Lim, K.J.
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1478-1480
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    • 1998
  • Inception and propagation of electrical tree and properties of partial discharge(PD) pulses accompanying with tree in low density polyethylene were discussed. We observed the characteristics of process of electrical tree by using optical microscope and investigated the statistical characteristics of the PD pulses by analyzing PD quantities and distribution patterns. The PD pulses were analyzed by q-n, $\phi$-n and $\phi$-q distribution. The statistical operators used were skewness(s), kurtosis(k) and average phase angle. The skewness and average discharge phase angle of PD pulses increased as the Propagation of tree. The kurtosis was about 1.8 at the Inception of tree, but It increased as the propagation of tree.

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Three-Temperature Modeling of Carrier-Phonon Interactions in Thin GaAs Film Structures Irradiated by Picosecond Pulse Lasers

  • Lee Seong-Hyuk;Lee Jung-Hee;Kang Kwan-Gu;Lee Joon-Sik
    • Journal of Mechanical Science and Technology
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    • v.20 no.8
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    • pp.1292-1301
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    • 2006
  • This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results, it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated. For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser irradiation.

Development of FROG Hardware and Software System for the Measurement of Femto-Seconds Ultrashort Laser Pulses (지속시간 펨토초 수준의 빛펄스틀 재는 이차조화파발생 프로그(SHG FROG) 장치 개발)

  • 양병관;김진승
    • Korean Journal of Optics and Photonics
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    • v.15 no.3
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    • pp.278-284
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    • 2004
  • A Second Harmonic Generation Frequency Resolved Optical Gating(SHG FROG) system was developed. Its performance test shows that it is capable of accurately measuring the temporal evolution of the electric field, both amplitude and phase, of femtosecond light pulses. For the retrieval of the temporal evolution of light pulses from their spectrograms obtained by using the FROG system, Principal Components Generalized Projection(PCGP) algorithm is used and in addition we used additional constraints of second-harmonic spectrum, marginals in frequency and time-delay of the spectrogram. Such modification of the software brings about significant improvement in speed and stability of the pulse retrieval process.